directly results in catastrophic damage to the timeline, requiring immense effort and jumping-through-hoops to even halfway-repair, OR

is ITSELF a direct result of some sort of catastrophic accident so gigantic that it can only be corrected by ALTERING HISTORY ITSELF.

Let's take a typical example.

One fine day in 2027, your son, little Johnny X, stole Doc Atom's prototype Time Scooter to see what his doddering parents were really like when they were young. He went back to 2007 and met you! Keeping his real identity a secret, he set you up with the stunningly attractive bloke or gal you had always moped over but never had the nerve to ask out, and like a flash, you were married and having a kid.

Johnny returned to the future, his mission accomplished. Only problem was, time has been subtly altered by young Johnny's interference! You were going to get together anyway, but because of Johnny, you met at the bar instead of the disco, you got married on July 23rd instead of the 22nd, and nine months later your firstborn kid turned out to be a girl.

Since she was conceived on a different day, she was conceived with different sperm. She got a different set of DNA so of course she turned out to be a different person.

20 years later, kooky Doc Atom invented his Time Scooter, but young Jenny X had band practice that evening. She never stole the Time Scooter and never went back in time.

But nevertheless, Johnny X arrived from the past, returning to the exact moment he left.

At which point he realised that, in 2007, history had been fundamentally altered by a guy who was never born.

And the universe realised this too, belched an unhappy error message and ceased to exist.

"So? Time travel hasn't been invented."

YET. By definition, time travel wioll haven be invented at every single point in history simultaneously. If, at some point in the future, time travel will be invented, then the time travellers could - in fact, MUST - be here RIGHT NOW, observing, recording, taking part in, meddling with and generally screwing up history as we think we know it.

This is a real risk. This could happen at any second. It has ALWAYS been a risk and will be in perpetuity.

Unless we act "now".

Our mission

To preserve the integrity of the spacetime continuum, I hereby petition the governments of the world to immediately enact laws banning the research and practice of time travel.